The present invention relates to topical cosmetic compositions that incorporate materials to stimulate DNA repair mechanisms to repair skin cells. The disclosed compositions and methods may prevent, reduce, or reverse signs of premature aging, and/or improve the aesthetic appearance of skin. Use of the compositions may stimulate the skin's natural ability to recover from environmental stresses and prevent signs of premature aging. The compositions include natural active ingredients derived from natural plant materials, as well as enzymes for repairing DNA damage.
The skin is made up of two major layers. The stratum corneum, or epidermis, is the top or outer layer of the skin. The primary function of the stratum corneum is to provide a protective covering and retard evaporative water loss from the aqueous interior. This is commonly referred to as the barrier function. The stratum corneum protects against mechanical insults, the ingress of foreign chemicals and assaults by microorganisms. It also provides the first defense against ultraviolet light, screening out more than 80% of incident ultraviolet B irradiation.
The dermis lies under the epidermis and makes up 90 percent of the skin's thickness. The dermis contains a dense meshwork of collagen and elastin, providing strength and elasticity to the skin. Fibroblasts constitute the main cell type present in the dermis. Fibroblasts are responsible for synthesis and secretion of dermal matrix components, including collagen, elastin, and glycosaminoglycans (such as hyaluronic acid). Whereas collagen provides strength to the skin and elastin its elasticity, glycosaminoglycans serve to keep the skin moist and plump.
To stay healthy, the skin must cope with changing environmental conditions, while simultaneously repairing damage. Environmental factors play a chief role in aging, wrinkles, skin discolorations and degenerative skin conditions. Exposure to sunlight and UV radiation are major factors resulting in skin damage, accounting for 90% of the symptoms of premature aging. Importantly, exposure to oxygen, sunlight, and other environmental or lifestyle stresses induces the formation of free-radicals. Free radicals can cause wrinkles by activating metalloproteases, such as collagenases, that are responsible for breaking down the skin's connective tissues (collagen and elastin). The result is premature aging. Free-radical damage can also cause a reduction in the thickness of the dermal layer. This can cause the skin to slacken. The slackening of the skin is the first and most visible sign of aging and a cause of wrinkles and lines.
Sunlight also can cause the accumulation of abnormal elastin by triggering the overproduction of metalloproteinases. Normally, metalloproteinases remodel sun-injured skin by manufacturing and reforming collagen. Repeatedly subjecting the skin to this imperfect rebuilding process may lead to formation of wrinkles or solar scars. Exposure to the sun also can rob the skin of essential moisture and create a stressed barrier that does not function properly. As moisture loss and irritation increase, the skin becomes sensitive, scaly, and dry.
Although oxygen and sunlight constitute the principal sources of free-radical damage, other contributors include cigarette smoke, environmental toxins, herbicides, pesticides, weather, diet, stress, sleep deprivation, excessive alcohol consumption, and pollution.
UV radiation from the sun may also damage DNA and may bring about several detrimental effects including cell death, mutation and neoplastic transformation. Studies indicate that some of these deleterious effects are due to the formation of two major classes of bipyrimidine DNA photoproducts, cyclobutane pyrimidine dimers (CPDs) and (6-4) photoproducts (6-4 PPs). Organisms have evolved several different pathways for removing CPDs and 6-4 PPs from cellular DNA. These pathways include various excision repair pathways which can be highly specific or nonspecific for CPDs and 6-4 PPs.
In view of the many detrimental effects impacting the skin, there is a demand for cosmetic compositions and cosmetic methods for improving the appearance and condition of skin. Consumers seek “anti-aging” cosmetic products that treat or delay the visible signs of actual aging and weathered skin, such as wrinkles, lines, sagging, hyperpigmentation and age spots. Consumers also seek other benefits from cosmetic products in addition to anti-aging benefits. For example, the concept of “sensitive skin” has raised the demand for cosmetic products that improve the appearance and condition of sensitive, dry and/or flaky skin, and that soothe red, and/or irritated skin. Consumers also desire cosmetic products that treat spots, pimples, blemishes, and the like, or that reduce the risk of skin cancer.
In spite of the various anti-aging cosmetic products on the market for the treatment of skin, there remains a need for effective topically applied cosmetic compositions that provide anti-aging or rejuvenating benefits to the skin, hair and/or nails using natural ingredients as active components. Unnatural, chemically-synthesized products may be perceived as being environmentally or personally unsafe. In contrast, natural products are perceived as pure, mild, and superior to chemically synthesized products. Natural based products extracted from plants or herbs are believed to contain antioxidant/free-radical scavenging agents that can neutralize the effects of free-radical damage. Additionally, they can contain agents that stimulate the synthesis and restoration of damaged connective tissue structures in the dermis and barrier function in the epidermis.
However, delivering a cosmetic benefit from “natural” sources, such as plants or herbs, is not trivial. Deriving a real benefit from such sources requires identification of specific plant/herbal extracts or ingredients, their minimum active concentrations, and their additive or synergistic activities in combination with other ingredients to impart anti-aging and/or skin improvement benefits.
The present compositions further address the frequent irritation problems associated with exfoliating agents such as retinoids (e.g., tretinoin, retinol and retinal), carboxylic acids including α-hydroxy acids (e.g., lactic acid, glycolic acid), β-hydroxy acids (e.g., salicylic acid), α-keto acids, acetic acid and trichloroacetic acid, 1-pyrrolidone-5-carboxylic acid, capryloyl salicylic acid, α-hydroxy decanoic acid, α-hydroxy octanoic acid, gluconolactone, methoxypropyl gluconamide, oxalic acid, malic acid, tartaric acid, mandelic acid, benzylic acid, gluconic acid, benzoyl peroxide and phenol, among others. Exfoliants and other ingredients may also increase the skin's sensitivity to environmental conditions such as sunlight, wind, cold temperature and dry air, or may exacerbate the irritation attributable to a pre-existing skin disease.
The present invention therefore provides cosmetic compositions for topical use that have anti-aging, anti-oxidant, anti-irritant, anti-inflammatory, and/or aesthetic improvement properties. The cosmetic compositions of the present invention may reduce irritation problems that may be encountered with conventional exfoliating agents.